User's Manual

455U-D Radio Modem Module User Manual
Page 46 © Jan 2008
If using Hayes commands, Dual Redundancy is set via the AT#O command (“set output
function”).
♦ to force a changeover from primary to secondary, use command AT#O5.
♦ to force a changeover from secondary to primary, use the command AT#O6.
♦ the status of the Dual Redundant system is displayed in register S33.
S33 Value Dual Redundant State
2 Active Primary
3 Active Secondary
4 Active Primary – no secondary detected
5 Inactive Primary
6 Inactive Secondary
I/O LED indication for Dual Redundancy operation
The I/O LEDs on the two modules indicate the status of the dual redundancy operation. The
LEDs should flash in synchronization. If they do not, the wire connecting the DIO of the two
modules may be disconnected.
LED Sequence Redundancy Status
1½ seconds on, ½ second off. Normal operation. Primary is active, Secondary is
inactive but functional
1 second on, 1 second off Secondary Fault. Primary is active, Secondary is
inactive and has a fault
½ second on, 2 seconds off Secondary is active, Primary is inactive and has a fault
Always On Hardware fault on I/O Circuit or module fault.
Disconnect wire to determine which module is
functional.